Electroplating copper



UNIT ED STATES PATENT OFFICE.

IVILLIAM HOLLINGSHEAD, OF BRONXVILLE, NEW YORK, ASSIGNOR TO JAMES Gr. BATTERSON, OF HARTFORD, CONNECTICUT.

ELECTROPLATING COPPER.

SPECIFICATION forming part of Letters Patent No. 557,816, dated April *7, 1896.

Application filed September 23, 1889. Renewed November 5, 1895 Serial No. 568,061. (No specimens.)

To aZZ whom it may concern:

Be it known that I, WILLIAM B. HoLLINcs- HEAD, of Bronxville, county of lVestchester, State of New York, have invented a certain Improvement in Electroplat-in g Copper, of which the following is a specification.

The invention consists in an improved electroplating-bath to be used in electrically depositing copper from an anode upon plates or objects of another metal placed in the bath in the ordinary manner.

The primary and distinguishing feature of the bath hereinafter described is that in active operation it is not appreciably or materially depleted of its copper; but on the contrary its strength remains practically constant, while it serves as a vehicle for conveying the copper from the anode to the cathode or object upon which it is deposited. Because of this stable quality of the bath I call it a conveyor.

In compounding the bath I may proceed as follows, using substantially the proportions hereinafter stated, the proportions being such as to produce a bath having the characteristic above mentioned: I take, first, twelve (12) parts, by weight, of ammonium cyanid and dissolve it in about three times its bulk of water at a temperature of from 100 to 110 Fahrenheit; second, sixty-one (61) parts, by weight, of potassium tartrate (neutral) and dissolvcit in about three times its bulk of water at a temperature of about 110 Fahrenheit; third, twenty-seven (27) parts of a mixture of oxid of copper and water mixed to a pasty consistency. The last two ingredients are then mixed, the potassium tartrate forming the solvent for the cupric hydrate. The firstnamed ingredient, ammonium cyanid, is then added to the mixture, and then a quantity of water equal in bulk to about three times that of the other two ingredients is added to reduce the bath to a proper strength for use.

I have found that Rochelle salts can be used in place of the potassium tartrate in substantially the same proportions, and I consider it, for the purpose of the invention and the claim herein, an equivalent of potassium tartrate that may be substituted in the compound for the latter element, in which case the ingredi- 5o ents would be prepared and mixed in the manner above stated.

The bath or conveyer above described is stable, constant, and active because it contains no ingredients that will be decomposed 5 5 on the passage of the electric current through the bath to form insoluble salts of copper that will be precipitated in the bath and not again be taken up or redissolved. The supply of metal deposited is taken from the anode and not from the oxid of metal or salt of metal contained in the solution bath or conveyer. This is caused by the solution bath or conveyer having a salt which oxidizes the anode and is also a solvent or an absorbent for said 65 oxid and also a conveyer. The bath is therefore not depleted of its copper, but remaining practically constant serves as a vehicle or conveyer by or through which the copper is transferred from the anode to the cathode.

I may give as a further explanation of the fact that there is no material precipitation of insoluble copper from this bath the presence in the bath of a salt that oxidizes the anode during the passage of the current and also acts as a solvent for the oxid. As a result of this characteristic-viz., practical constancy or uniformity of strength of the bath I employ-the deposition of the copper is regular, uniform, and far more perfect and dense than can be obtained from the use of baths varying in strength during operation.

I claim as my invention The herein-described bath for copper electroplating composed of twelve parts of ammonium cyanid, sixty-one parts of potassium tartrate (neutral), twenty-seven parts of a mixture of water and 'oxid of copper mixed to a paste, and water, compounded substantially as set forth.

WILLIAM B. HOLLINGSHEAD.

lVitnesses A. B. JENKINS, IV. E. SIMoNDs. 

